Power transmission



Oct. 5, 1948. A. M. LANE `ETAI.

PWER TRANSMISSION 2 sheets-sheet 1 Filed Dec. 21, 1945 ma .i

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H7555? diam/ve' HND 17555.97' AJ. me Br M K. Hr ram Patented oct. 5, 194s POWER TRANSMISSION Albert M. Lane, Kingston V. Kirkpatrick.' and Robert A. Erskine, Detroit, Mich., assignors to' Vickers Incorporated, Detroit, Mich., a corporationof Michigan Application December 21, 1945Serial No. 636,339

This invention relates to power transmissions,

particularly to those of the type comprisingtwo oramore fluid pressure energy translating de.- vices, one of which may function as a pump and another as a fluid motor.

This invention is more particularly concerned with imparting a reciprocating movement to a reversible fluid motor to which is mechanically attached a load device, such as a slide or table of a grinding machine, and automatically controlling such movement so as to provide a uniformly controlled stopping and restarting of the motor at a predetermined point together with a smooth acceleration and deceleration of saidl motor. y

In the operation of a reciprocating grinding machine the slide or table may carrya clamped- Work piece to and from 'a stationary grinding tool or may carry the grinding tool to and from a stationary work piece. During such operation itis necessary to i-mpart a continuous reciprocat-I 19 claims. (ci. io- 52) 2 controlled, constantly` accurate deceleration, stopping, restarting and acceleration of the'reversible fluid motor'at each end of the motor stroke, and which is completely adequate in itself to -meet varying operating conditions.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of theA present invention is clearly shown.

In the drawings:

Fig.l 1' is a diagram-matic view of a' hydraulic transmission incorporating a preferred form of the present invention.

Figure 2 is a diagrammatic-view of the same hydraulic transmission shown in Figure 1 but ing motion to the motor, and some means must be provided for automatically reversing the motor at the end of each stroke until the work piece has been ground to the required size.

It has been a problem in the-past to provide a l unitary control panel for use in a hydraulic transmission for operating a grinding machine which would vnot only be simple in design* and contain a minimum number of control valves but which at the saine time'would be appropriate to perform effectively under a variety of operating conditlons. yIt has also been a problem to design a simple-control panel for use in a transmission as mentioned above which not only would provide for smooth accelerationand deceleration of the motor but which would automatically control the range of movement of the motor stroke and consistently stop the motor always at the same point during its operational stroke.

It is an object of this invention to provide an improved unitary control panel for use in a hydraullc transmission containing a reversible fluid showingl the parts in-a different position.

Referring now to Figure 1, there is shown a pump I0 which may be driven by an electric motor I2. Pump I0 is connected'to a tank I4 b y a suctionrconduit I6 and connected to a pressure port. I8 of a unitary control panel 28 by means of a delivery conduit 22. Panel 20 also has a tank port 24 connected to tank I4 by means of a conduit 26 and motor ports 28 and 38 connectedfio 'opposite ends of a reversible fluid motor 32-fby means of conduits 34 and 38. f 1;-1.

Incorporated in pump delivery conduit 22 is a combined flow control and relief valve 38 ywhich serves the dual purpose of regulating the amount `of fluid Aflowing to motor 32 from pump Ill so as x to regulate the speed of motor 32 and also limits the pressure in conduit 22 to a'- predetermined maximum by exhausting' excessive fluid under pressure to tank I4 by means of an exhaust conduit'40. Valve 38 is well known in the prior art 'y and preferably is constructed in accordance with motor which contains a minimumnumber of opcratlng controls and parts for automatically producing and controlling a continuous reciprocating movement' of saidmotor.

It is also an object of this invention to provide a unitary control panelA especially adapted for use in a hydraulic transmission for operating grinders which will dispense with a large amount of piping, connections and valves. l

It is also an object of this invention to provide -a control panel for a transmission, as above mentioned, which will produce an automatically the patent to Vickers, No. 2,102,865. Amanuallyoperated, two-way control valve 42 is connected to valve 38 by means of va conduit 44 and to tank I4 by means of a conduit 46 so as to provide a 'controlling means to 4vent the control chamber of vvalve 38 to tankI4 in order to completely unload pump I0 to stop motor 32 at the end of an operation or to lclose said vent in order to start said motor at the beginning of an operation.

' Panel 28 consists of a body 48 containing a longitudinal bore in which is shiftable a pilot valve 52 and a longitudinal bore 54 in which' is shiftable a reversing valve 56. Reversing valve 56 is comprised of a spool 58 having grooves 68 and 62 to the left and right of its central porftion, grooves G4 and 68 spaced apart from grooves `IIl and 62, respectively, and grooves 68 and 'Ill spaced apart from grooves 64 and 56 and located near each end of spool-58. Spaced along bore 54 is a pressure port 12, motor ports 14 and 16 and return ports 18 and 80. Spool 56 has duplicate longitudinal bores v82 and 84 extending from each end thereof to duplicate radial passages 86 and 88. y Y

Reversing valve 56 is adapted to be operated by huid pressure admitted alternately to chambers 80 and 82 located in bore 54 at each extreme end of spool 58. A passage 84 in communication with chamber 80 and a passage 86 in communication with chamber 82 Ahave duplicate check valves 88 and |00 and similar adjustable needle valves |02 and |04 interposed in said passages for the Well-known purpose of controlling .the entrance and exit of iiuid to and from chambers 80 and 82 and regulating the speed of spool 58.

A passage |06 having an external entrance 2|0 normally blocked by a solid plug |08 is connected to pressure port I8 and branches so as to connect to similar ports and |1|2 spaced along bore 54. A passage ||4 connected. to pressure port |8 not only intersects bore 54 at reversing valve pressure port 12 -but also branches to connect tc similar ports |I6 and I8 spaced along bore 50. The passage ||4 may be closed beyond the pressure port 12 at a point indicated by the numeral I|8 by a solid plug, not shown, when the reversing valve is to' be operated by substitute means to -be later described. Duplicate return passages |20 and |22 connect the return ports 18 and 80 of reversing valve 56 with duplicate pilot valve return ports |24 and |26 spaced along bore 50. Similar ports |28 and |30 spaced along bore 54 are connected to duplicate ports |32 and |34 spaced along bore 50 by passages |36 and |88, respectively. Passages 40 and |42 connect duplicate ports |44 and |46 spaced along bore 54 with a passage |48 which is connected to duplicate ports |50 and |52 spaced along bore 50. Passage |48 is in' communication with an enlarged recess |54 which is connected to tank port 24.

Passages 84 and 86 which are connected to chambers 80 and 82, respectively, oi reversing valve 56 are connected to similar ports |56 and V|58 spaced along bore 50.

Pilot valve 52 consists of a spool |60 shiftable within bore 50. Spool |60 has two identical stepped bores |82 and |64 extending from the right and left end, respectively, of spool |60 to a centrally-located cut-out portion |66 which is in communication with recess |54. Bore |62 is in communication with a chamber |68 at the right end of spool |60 in bore 50, and bore |64 is in communication with a chamber at the left end of spool |60 in bore 50. Similar passages |68 and |1| connect similar ports |13 and |15 spaced along bore 54 with chambers |68 and |10. Duplicate check valves |12 and |14 are mountedin bores |62 and |64 to permit entrance or fluid to chambers |68 and |10 during initial mechanical movement of -pilot valve 52 and to alternately block now of pressure iluid from said chambers to tank I4 when the pilot valve 52 is subsequently 3 |60 to the right and left of portion |66 are adapted to alternately gradually close pilot valve return ports |26 and |24 depending upon a shifting of pilot valve 52 tothe right or left during operation thereof.

Grooves 60 and 82 of valve spool 58 control the delivery of fluid to and from motor 32 by directing uid to the motor through pressure port 12 alternately to motor `ports 14 and 16 and to tank I4 by) directing fluid returning from the motor 32' through either motor ports 14 or 16 to return ports 80 or 18.

' The reversing valve return ports 18 and 80 are connected to the pilot valve return ports |24 and4 tions I82 or |80gradually passing over said return ports so as to decelerate the motor 32.

Groove 64 of spool 58 controls the ports I||0 and |28, and groove 66 controls ports ||2 and |30, so as to direct pressure uid in passage |08, which is connected to ports I|0 and ||2, to pilot valve ports |32 or |34 in order to rapidly complete the operation of pilot valve 52 after a certain range of controlled mechanical movement thereof. During the initial mechanical movement of pilot valve 52, the ports |32 and |84, which are connected to reversing valve ports |28 and |30 by means of passages |36 and .-l38, are blocked from communication with pilot valve ports |18 and |16. After a certain range of rightward movement of pilot valve 52, ports |18 will register with port |32, and, after a certain range of leftward movement thereof, ports |18 will register with port |34 so as to admit pressure fluid in either Ipassage |36 or |88 to chambers |10 or |68 of pilot valve 52 in order to rapidly complete the operation of pilot valve 52.

Grooves 68 and '|0 of spool 58 merely permit the passage of fluid to either chamber |10 or |68 of pilot valve 52 by means of passages |42 or |40 when a substitute valve means is used to control pilot valve 52. When pilot valve 52 is initially mechanically operated and completely operated hydraulically, grooves 10 and 68'of spool 58 will di- 4 rect iluid discharging from chambers |68 or Y|10 vduring the shifting of said valve rightwardly or lettwardly to passage |48 by means of either passage |40 or passage |42.

Similar grooves |84 and v|86 in spool |60 control the admission of pressure iluid to passages 84 and 86 in order to control the operation of reversing valve 56. The ball end ot a rod |88 fits into portion |66 and secured to rod |88 is a rotatable shaft to which is rigidly fastened two arms |82 and |84.

Motor 32 contains a piston |88 to wihich is secured a piston rod |88 attached to each end of which is a table slide 200. Adjustably mounted on slide 200 is a pair of dogs 202 and 204. The arms |82 and |84 and dogs 202 and 204 are located in such a plane that, after a certain leftward range of movement of piston |86, dog 204 will contact arm |84 and, after a certain rightward range of movement of piston |86, dog 202 will contact arm |82 inporder to mechanically initiate operation ci pilot valve 52 in each direction.

Substitute means for operating pilot valve 52 entirely by pressure fluid are provided by external connections 205 and 208 which are normally 5 f plugged. If for some reason it is undesirable to produce the snap action of pilot valve 52 by pressure fluid directly from pump I0, a different source of -pressure fluid may be connected to the external entrance 2|0 of passage |06, in which case a restriction plug is inserted in placeof solid plug |08 in thepassage |06. If connection 2I0 is used, a restriction plug 220 in the passage |06 ahead of the pressure port I8 is removed and a solid plug inserted in its place.

If it is desired to operate an additional valve device under the control oi' panel 20, external connections 2|2 and 2|4 are provided for that purpose. If it is desired to substitute another source of pressure to operate. reversing valve 56, an external connnection 2|6 containing a check valve 2 I8 is provided for that purpose, anda solid plug would be inserted in the passage ||4 at the point indicated by the numeral I9.

Referring now to Figure 1, in operation'with the electric motor I2 running and operating pump |0 and with control valve 42 shifted so as to vent valve 88 to tank I4, pump I0 will -be unloaded, motor 82 wil1`be stopped, and the full delivery of pump I0 will be exhausted to tank I4 through valve 38 and conduit 40. n

If control valve 42 is shifted so as to block the control vent of valve 88, pump delivery will be directed by means of delivery vconduit 22 through valve 88 'to the pressure port I8 of valve 20. In the position shown, piston`|96 of motor 82 has already completed a rightward movement, and pilot valve 52 and reversing valve 56 have been operated completely so as to direct fluid to motor 82 to shift piston |96 thereof leftward. Pressure fluid from pump I0 entering pressure port I8 is directed by reversing valve 56 because of groove |24, recess |54, tankport 24 and conduit 26 to` tank I4. Pressure fluid entering pressure port I8 also enters passage I I4 and by means of groove |84 in pilot valve 52 flows through p orts ||8 and |56 thereof and passage 94 through check valve 99 to chamber 90 of reversing valve 56.

Due to the fact that reversing valve 56 has already completed a leftward movement thereof.;

the further admission of pressure fluid to chamber 90 by means of the ports and passages hereinbefore mentioned will have no effect. Also, due to the fact that pilot valve 52 and reversing valve 56 have completed their leftward movement, pressure iluid entering pressure port I8 and flowing through versing valve 56 from flowing into'either port |44 or port |80. Fluid in passage |06 flowing lthrough ports ||0 and |28 of reversing valve 56 to passage |86 is blocked at port |32 by pilot valve 52. Fluid in passage |06 is prevented from flowing out the optional entrance 2 I 0 by the solid plug |08.

As piston |96 continues its leftward movement, the amount of iluld being directed by panel 20 to the right end of motor 32 will be regulated by valve 88 so as to regulate the speed of piston |96. Due to the fact that dog 202 is in a differentplane than arm |94 and will pass thereby, piston |86 will continue its leftward movement, and dog 204 will 'assunse speed of mvement will be determined by th speed of movement'ofpiston'I96. j 1

A's pilot valve 52 shifts rightward, cut-away portion |82 of spool I60'will gradually pass over return port |24, gradually making the opening thereof smaller. Due to the fact that fluid being discharged from the left end of motor 82 must return to tank I4 through return port |24, the

gradual closing of return port |24 will gradually 10 pilot valve 52, as this fluid must return to tank 10, port |44, passage |40, passage |48, recess |54,

. charging iluid from the right end of reversing restriction 220 vand passage |06 is blocked by re contact Yarm |94, rotating shaft |90 to which is attached rod |88. Upon dog 204 contacting arm. |94, pilot valve 52 will shift to the right, and its I4 by means of passage |69, port I 18, groove 10,

port |44, passages |40 and |48, recess |64, passageA |66 and check valve |14. t

Just before return port |24 is completely blocked, ports |18 will register` with port |82, and pressure fluid in passage |86 which previously had been blocked by pilot valve 52 may now enter bore |64 and chamber |10 and rapidly complete the rightward movement of pilot valve 52. During this rapid completion of operation of pilot valve 52, return port |24 is completely blocked so as to instantly stop motor 82. Check valve |14 cofoperates in this rapid completion of operation oi' pilot valve 52 by preventing pressure fluid escaping from vbore |64 to portion |86.

While pilot valve 521s shifted rightward, fluid in chamber |68 and bore |62 may discharge to tank 4 by means of passage |69, port |18, groove tank port 24a-nd conduit 26.

Upon pilot valve 52 shifting completely tothe right, fluid under pressure from pump I0 entering pressure port I8 and passage ||4 which had been previously blocked at port I I8 is now free to flow through port |58 by means of groove |86 and by means of passage 96 and check valve |00 tov chamber 92 and loore 84 and shift reversing valve 56 to the right. The initial movement of reversing valve 56 rightward will be rapid because disvalve 56 in chamber 90 and bore 82 does not have to ilow through needle valve |02 but has a free outlet to tank I4 byv means of bore 82, vpassage 88, return passage |22, return port |26, portion |80, recess |54, tank port 24 and conduit 26.`

in speed according to the original adiustmentof needle valve |02.v Fluid discharging from the right end of reversing valve 56 will reach tank I4 l by means of needle -valve |02, passage 94, port |56, groove |84,` port |52. passage |48', recess |54, tank port 24 and conduit 26.

When needle valve |02` becomes eilective to regulate the speed of reversing valve 56 right? wardly, the changeover. of the reversing valve ports is` just taking place, and pressure fluid entering pressure port 12 from pump vI0 is gradually allowed to enter-port 16through groove 60,

dependent upon the speed of opening of motor port 16 which is dependentupon the original ad ing fluid from the right end of motor 82 may flow to tank |4 by means of conduit 86, port 80, port 14, groove 62, port 80, return-passage |22, return port |26, portion |80, recess |64, tank port 24 and conduit 26. Piston |96 will continue to smoothly accelerate to'a speed of movement dictated by the original setting of valve 88. Piston |86 will continue to shift rightwardly at such regulated speed, and dog 204, being on a different plane than arm |92, will pass thereby, and a continued movement of piston |86 results in dog 202 contacting arm |62.

Pilot valve 62 will begin to shift to the left as dictated by the speed of piston |96, and the continued movement of pilot valve 62 to the left results in cut-away portion |80 slowly passing over vreturn port |26 to gradually close the sizeof opening of said port. This results in gradually increasingly restricting the flow of iiuid discharging from motor 82 through return port |26 to tank I4 and again has the eil'ect of smoothly decelerating motor 82. During initial leftward mechanical movement of pilot valve 52, chamber |68 Vand bore |62 thereof are supplied with fluidv in the same manner as bore |64 and chamber |10 were supplied with fluid during initial rightward -bore |62 to portion |66. Fluid in bore |64 and chamber has a free outlet to tank I 4 by means of passage |1|, port |16, groove 68, port |46, passages |42 and |46, recess |54, tank port 24 and conduit 26. This snap-action completion of operation of pilot valve 62 results in return port |26 being suddenly andA completely closed to discharging fluid from the right end of motor 32, and the rapid complete shifting of spool |60 again results in taking advantage of the greatest amount ofV sealing space in the shortest possible time so as to instantly stop the movement of piston 96.

Upon the completion of movement of spool |80 -leftwardly-as shown in `Figure l, fluid under pressure from pump I0 delivered through pressure port I8 and port 12 into passage ||4 is now free to enter chamber 90 and bore-82 of reversing valve 66 by means of port ||8, groove |84, port |66, passage 94 and check valve 98. Discharging fluid from chamber 92 and bore 84 of reversing valve 66 initially has a free outlet to tank |4' by means of passage 86, port 18, return passage |20, pilot valve return port |24, portion |82, recess |64, tank port 24 and conduit 26. This rapid movement of spool 68 continues until passage 86 is blocked from communication with return port 18, at which timeiluid from chamber 92 and 'bore 84 must flow to tank I4 through needle valve |04 so as to regulate further movement of spool 68 in a leftward direction.

This operation of reversing valve 66 in a leftward direction is identical with the operation of reversing valve 66 in a rightward direction as Dreviously described. The changeover of communication between the reversing valve ports will again take place just as the speed of spool 68 is beginning to be regulated. Communication between reversing valve pressure port 12 and motor port 14 is opened gradually and results in a smooth acceleration of motor 82. When needle valve |04 becomes eiective so as to regulate the speed of movement of spool 58, discharging fluid from chamber 82 and bore 84 must flow to tank I4 by vmeans of needle valve |04, passage 06, port |68,y

groove |86, port |60, passage |48, recess |64, tank port 24 and conduit 26. This automatic reciprocation of motor 82 continues until the grinding operation has been completely performed, at which time motor 82 may be stopped by shifting valve 42 to -vent valve 88 to tank I4, and the complete delivery of pump l0 will be unloaded to tank |4 by. means of conduit 22, valve 88 and conduit 40.

It should be noted that pilot valve 62 is initially operated by mechanical means, that is, contact of either dog 204 with arm |94 or of dog 202 with arm |82 near the completion of each stroke of the motor 82, and that, duringthis initial mechanical operation thereof, the return ports |24 and |26 are alternately gradually closed to discharging uid from the motor 82 so as to smoothly decelerate said motor.

It should also be noted that, just before the return port |24 or the return port 26 of pilot valve 62 isv completely blocked, the operation of pilot valve 62 is rapidly completed by means of pressure fluid so as to take advantage of the greatest amount of sealing overlap, preventing overtravel of piston |96 and consistently stopping motor 82 at a predetermined point during operation thereof.

It should also be noted that the momentary dwell at the end of each motor stroke is greatly shortened by the initial rapid operationof reversing valve 66 and that this rapid v,movement -of reversing valve 66 will only continue to the to the action of'either needle valve |02 or |04 when passages 86 or 88 are blocked from communication with return ports 18 or 80 so as to restart and produce a smooth acceleration of motor 82 It should also =be noted that the pilot valve and the reversing valve each have two diierent steps of operation and that each one of these steps of operation are under separate means of control. The rst step of operation of the pilot valve is controlled relative to the speed of the motor in order t'o gradually close a pilot valve returnport through which uid is returning from the motor. The second step of operation of the pilot valve, namely, rapid movement thereof to a point of completion of operationl followed by the first step of operation of the reversing valve, namely, rapid movement thereof to the point of changeover of the reversing valve ports, may be considered as intermediate steps of operation. The second step of operation of the reversing valve, namely, a movement thereof controlled by an adjustable restriction during the changeover of the lreversing valve ports, is thev final step of operation. The rst step of operation of the pilot valve results in a smooth, controlled deceleration of the motor, while the second step of operation of tro led acceleration ofthe motor.

In addition, substitute means have been provided i'or operating pilot valve 02 completely by fluid pressure, in which case dogs 202 and 204,

arms |92 and l, lod |88 and shaft |90 will be removed. In such case, external connection ports' the reversing valve results in al smooth, con- 206 and 208 which are normally plugged will be have a snap completion of operation of pilot valve l 52 and a substitute source of pressure other than that from pump i0 be used for such action, this substitute source of pressure may be connected into external connection port 2| 0, which is normally plugged, a restriction plug of suitable proportion inserted in place of the solid plug |08 and a solidplug inserted in the place of the restriction plug 220.

If for some reason it is desired to initially operate pilot valve 62 by means of mechanical linkage with motor 32 and to rapidly complete the operation thereof by a source of fluid pressure other than directly fr om pump |0, said substitute source of pressure may be connected into exter` nal port 2|0, a restriction plug inserted in place of solid plug |08, and 'restrictionplug 220 would be replaced by a solid plug.

Also, if it is desirable to operate another load device in addition to slide 200, connections are provided for such a purpose at ports 2|2 and 2 I4.

' Conduite would be connected to ports 2|2 and 2|4and to the load device, and the same source oi' pressure, namely. Dump I0, would be utilized to operate said load device, and panel would control the operation of said load device so as to completion of each stroke of motor 32. Substitute means for operating reversing valve 00 have also been provided by an external connection port 2|6 .having a check valve 2|8Yto which a source of pressure fluid may be .connected, and in such case a solid plug may be inserted in the passage llt at the point indicated bythe numeral IIS. When the operation is such as is shown in Figures l and 2, however, substitute external connection ports 206, 208, 2|0, 2|2, 2M and 2|6 are not in use and consequently are plugged.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood thatother forms might =be adopted, all coming within the scope o f the claims which follow.

What is claimed is as follows:

1. In a hydraulic power transmission system having -a pump and a fluid motor and supply and return connections for the motor,` the' combination of a first shiftable valve element,v means thereon for controlling the cut-oil of return fluid from the motor, a second shiftable valve element, means thereon for controlling the reversal of the supply and return connections to the motor, means operated bythe motor for shifting the first element at a controlled speed to an intermediate position,` means for shifting the first element rapidly 'through the remainder of its stroke, means controlled by the first element for initiating a rapid'movementof the second element to an intermediate position, and means for causing passage4 |08l in l the shifting of the second element through the remainder of its stroke to take place at a controlled speed. 2'. In a hydraulic power transmission system having a pump and a fluid motor and supply and return connections for the motor, the combination of' a flrst shiftable valve element, means thereon for controlling the cut-oil of return fluid from the motor, a second shiftable valve element, means thereon for controlling the reversal of the supply and return connections to the motor, and

means for shifting each valve element in two separate steps. each step being under independent control. L

3. In a hydraulic .power transmission system having a pump and a fluid motor and supply and returnv connections for the motor, the 'combination of a hydraulically-operated, shiftable valve spool, means thereon for controlling the reversal `of thesupply and return connections tothe motor, a shiftable-valve element, means operated by the motor for automatically mechanically shifting the valve element at' a controlled speed to an intermediate position, means vcontrolled bythe valve element during the controlledspeed movement thereof for gradually cutting oil the flow of return fluid from the motor. means for hydraulically sliifting the,valve element rapidly through the remainder of its stroke, means controlled by the valve element for directing fluid to and from the valve spool for operating the' latter. means" for permitting a rapid shifting ofthe valve spool to an intermediate position, and means for oon produce a reciprocal movement thereof at .the

mainder -of its stroke, means controlled bythe valve element for directing fluid to andfrom the valve spool for operating the latter, means for trolling the speed of the valve spool through the remainder of its stroke.

4. In a hydraulic power transmission system spool, means thereon for controlling the reversal of the supplyand return connections tothe mo tor. a shii'tabie valve element, means operated by the motor for automaticallyy mechanicallyl shifting the valve Aelement at a controlled speed to an intermediateposltion, means controlled by the valve element during the controlled speed movement thereof for gradually cutting oil' the flow of return fluidfrom the motor. means controlled by the valverelement for hydraulically shifting the valve element rapidly through the repermitting a rapid shifting of the valve spool'to an intermediate position, and means for controlling the speed of the .valveI spool through the remainder of its stroke during the reversal of the supply and return connections to the motor.

5. A unitary control panel for use in a hydraulic power transmission having a uid pump and reversible fluid motor for causing the motor to operate in alternately reversing cycles and comprising in combination, a body, a rst shiftable valve element mounted therein, said first valve element including return ports through' which uid Vis 4adapted to flow from the motor, means on said first valve element for blocking said returnports. a secondshiftable valve element mounted in the body, means thereon for directing uid to and from said motor, means operated by the motor .for shifting the first element at a controlled speed to an intermediate position, means for shifting the first element rapidly through the remainder of its stroke, means controlled by the first element for initiating a rapid movement of the second eleb 1i ment to an intermediate position, and means'for causing `the shifting of the second element through the remainder oi' its stroke to take place at a controlled speed.

6. A unitary control. panel for use in a hydraulic power transmission having a fluid pump and reversible fluid motor for causing the motor to operate in alternately reversing-cycles and comprising in combination, a body, a first shiftable valvev element mounted therein. said rst valve element including return f ports through which fluid is adapted to flow from the motor, means on said iirstj valve element for blocking autogas l2 ation thereof for gradually closing a return port through which fluid is owing from the motor, means controlled by the pilot valve for rapidly r ompleting the operation thereof by pressure iluid Just before said return port is completely blocked,

a reversing valve. an adjustable restriction for controlling the speed of operation of the reversing said return ports, a second shiitable valve element mounted in the bodykmeans thereon for directing fluid to and from said motor, and means forshifting each valve element in two separate steps, each step being under independent control.

'1. A unitary control panel for use in a hydraulic power transmission having a uid pump and reversible fluid motor for causing the motor to operate in alternately reversing cycles and comprising in combination, a body, a pilot valve valve,A means forming a bypass around said restrlction, and means controlled by the reversing valve closing said bypass after a predetermined trolling said reversing valve, means for automatireciprocably mounted therein, said pilot valve including return ports through which uid is adapted to flow from the motor, means for ini- .tially mechanically operating the pilot valve vat each end of themotor stroke, means controlled by the pilot valve during initial mechanical operation thereof for gradually closing a return port through which fluid is flowing from the motor, means controlled by the pilot valve for rapidly completing the operation thereof by pressure duid after a predetermined range of mechanical movement thereof, and a iluid pressure operated reversing valve reciprocably mounted Ain said body controlled by the pilot valve for directing fluid to and from said motor.

8. A unitary control panel for use in a hydraulic power transmission having a uid pump and reversible uid motor for causing the motor to operate in alternately reversing cycles and comprising in combination, a body, a pilot valve reciprocably mounted therein, said pilot valve including return ports through which fluid is adapted to flow-from the motor, means for initially mechanically operating'the pilot valve at .each end of the motor stroke, means controlled by the pilot valve during initial mechanical operation thereof for gradually closing a return port through which fluid is owing from the motor, means controlled by the pilot valve for rapidly completing the operation thereof by pressure fluid after a predetermined range of mechanical movement thereof, a-fluid pressure operated reversing valve reciprocably mounted in said body controlled by the pilot valve for directing fluid to and from said motor, means for regulating the speed oi' operation of the reversing valve, means forming a bypass around said regulating means causing'rapid movement of the yreversing valve, and

ing said bypass after a predetermined rangeof reversing valve operational movement.

9. A unitary control panel for use in a hyl draulic power transmission having a iiuid pump and reversible fluid motor for causing the motor to operate in alternately reversing cycles-and comprising in combination, a body, a pilot valve reciprocably mounted therein; said pilot valve cally mechanically initiating operation of the pilot valve by the motor near the end of each motor stroke, and fluid pressure means controlled by the pilot valve for rapidly completing the operation oi' the pilot valve after a predetermined range of mechanical movement of said pilot valve.

l1. In a hydraulic transmission system the combination of a fluid pump, a reversible fluid motor, iluid supply and return connections between said pump and motor, and a control system contained within a panel in said connections for automatically causing the motor to operate in alternately reversing cycles,.said control system comprising a iluid pressure operated reversing valve for alternately directing fluid to and from opposite ends of said motor, means for regulating the speed of operation of the reversing valve,

means forming a bypass around said regulating means controlled by the reversing valve for closmeans, means controlled by the reversing valve for closing said bypass after a predetermined range of movement of said reversing valve, a pilot valve for controlling said reversing lvalve, means for automatically mechanically initiating operation of the pilot valve by the motor near the end of each motor stroke, and uid pressure means `controlled by the pilot valve for rapidly completing the operation oi' the pilot valve after a predetermined range of mechanical movement of said pilot valve.

12. In a hydraulic transmission system the combination of a fluid pump, a reversible-fluid motor, fluid supply and return connections between said pump and motor, and a control system contained within a panel in said connections for automatically causing the mot r to operate in .alternately reversing cycles, said control system comprising a iluid pressure operated reversing valve for alternately directing fluid to and from opposite ends of said motor. a pilot valve for controlling said reversing valve, said pilot valve- Vincluding return ports through which fluid is including return ports through which fluid is U adapted to ow from the motor, means for automatically initiating operation of the pilot valve by the motor near the end of each motor stroke, means controlled by the pilot valve during initial mechanical movement thereof for gradually closing a return port through which fluid is return- `ing from the motor, and fluid pressure means controlled by ,the pilot valve for rapidly completing the operation of the pilot valve after a predetermined range of mechanical movement of said pilot valve.

13. In a hydraulic transmission system th motor, fluid supply and return connections between said pump and motor, and a control system contained within a panel in said connections for automatically causing the motor to operate in alternately "reversing cycles, said control system comprising a iluid pressure operated reversa ing valve for alternately directing iluid to and4 from opposite ends of saidmotor, an adjustable restriction for regulating the speed of operation accorse combination of anula-pump, a reversible fluid 14 during initial mechanical .operation for4 gradually closing a pilot valve return port through which fluid is returning from the motor through a rel versing valve return'port, means controlled by the pilot valve after a. predetermined rangeoi mechanical'l movement for alternately opening a pressure chamber connection and rapidly completing the operation oi.' the pilot valve byv fluid ofthe reversing valve, means forming a bypass e around said adjustable restriction for producing rapid initial operation oi' sa'ld reversing valve..

means controlled by thg reversing valve for closing said bypass to cause said restriction to become effective after a predetermined range of rapid movement of said reversing valve, a pilot valve for controlling said reversing valve, means -for automatically mechanically initiating operation of the pilot valve by the motor near the end of eachA motor stroke, and iluid pressure means controlled by the pilot valve for rapidly completing theoperation ofthe pilot valve aftery a predetermined range oi mechanical movemen of said pilot valve. y f

14. A unitary control panel for use in' a hy' draulic power transmission having a. fluid pump and reversible uid motor for causing the motor to operate in alternately reversing cycles and comprising in combination, a valve block, a pilot valve reciprocably mounted therein, said pilot valve including return ports through which iluid is adapted to ilow from the motor, iluidpressure chambers at opposite ends of said pilot valve, connections for said chambers, a passage adapted to be connected to a source of pressure in pressure, whereby the pilot valve return port through which iluid is returning from the motor is suddenly completely blocked, an adjustable restriction for controlling the speed of operation of the reversing valve, means forming a bypass around said restriction for permitting rapid movement of the reversing valve, and means controlled by the reversing valve closing said bypass after a predetermined range of rapid movement thereof causingsaid restriction to become effective.

18, In a hydraulic power transmissionY system the combination oi' a pump, a reversible fluid motor', fluid supply and return connections between `the .pump and motor, land a control system contained within a panel in said connections for automatically causing the motor to operate in alternately 'reversing cycles, said control s'ystem-comprising a iluid pressure operated rethe 'system and to said connections, a iluid pressure operated reversing valve reciprocably mounted within said valveblock controlled by said pilot valve for directing iluid to and from said motor, said reversing valve including duplicate return-ports connected by passages to said pilot valve return ports, means for mechanically initiating operation of the pilot valve near each V ,end of the motor stroke, means controlled by the pilot valve during initial mechanical operation for gradually closing a pilot valve return port through which'fluld is returning from the motor through a reversing valve return port.

stop at a predetermined, during operation.

versing valve for reversing the ilow oi iluid to the motor, -a pilot valve for controlling said reversing valve, means for initially mechanically actuating the pilot zvalve by the motor near the end oi' a motor stroke, means controlled by the pilot valve during initial mechanical operation for smoothly deceleratlng said motor, and iluid pressure means controlled by the pilot valve for snap action completion of operation of said pilot valve afterk a predetermined range of mechanical movement thereof causing said 4motor to constantly uniform point 17. In a. hydraulic power transmission system the combination of a pump, a reversible fluid motor, uld supply and return connections between the pump and motor, and a control system contained `within a. panel in said connections for v automaticallycausing the motor to operate in alternately reversing cyclesfsaid control system comprising a .fluid pressure operated reversing valve for reversing the flow of fluid to the moand means controlledl by the pilot valve after a Y predetermined range of mechanical movement for alternately opening a pressure chamber con-v nection and rapidly completing the operation of the pilot valve by iluid pressure.

15. A unitary control panel for use-in a hydraulic power transmission having a fluidv pump and reversible iluid motor for causing the motor to operate in alternately reversing cycles and comprising in combination, a valve block, a pilot valve reciprocably mounted therein, said pilot valve including'r'eturn ports through which fluid is adapted to iiow i'rom the motor, fluid pressure chambers at opposite ends oi.' saidpilot valve, connections for said chambers, a passage adapted to be connected to a source of pressure in the' system and to said connections, a fluid pressure operated reversing valve reciprocably mounted Awithin said valve block controlled by said pilot valve for directing fluid to and from said motor, said reversing valve including duplicate return 'ports' connected by passages to said -pilot valve Areturn ports, means for mechanically initiating operation of the pilot valve near each end of the motor stroke, means controlled by the pilot valve 18. lin a hydraulic power transmission system the combination ola pump, a reversible iluid motor, fluid supply and return connectionsbetween the pump and motor, and a control system contained within a' panell in said connections for automatically causing the motor to operate in alternately reversing cycles, said control system comprising a iluid pressure'operated reversing valve for reversingthe ow of uid to the motor, a pilot valve for controlling said reversing valve,

.means for initially mechanically actuating the pilot valve by the motor near the end oi.' a motor initial me lhanical operation for smoothly decelerating said motor, iluid pressure means controlled by the pilot valve for snap action completion of operation of said pilot valve after a predeter mined range of mechanical movement thereof causing said motorto stop ata predetermined, constantly uniform point during operation, an

adjustable restriction for regulating the speed of the reversing valve, 'means forming a bypass around said restriction, and means for closing said bypass after a predetermined range oimovement oi' the reversing valve, said reversing valve restarting and providing a smooth acceleration of said motor.

19. A unitary control panel for use in a hydraulic power transmission having a iiuid pump and reversible iluid motor for causing the motor to`operate in alternately lreversing 'cycles and comprising in combination, a reciprocable pilot valve, said pilot valve including return ports through which fluid is adapted to flow from the motor, a reversing -valve adapted tol be operated by uid pressure and controlled by the pilot valve, said reversing valve including pressure and motor connections and return ports in communication with the pilot valve return ports, means adapted for initial mechanical operation of the stroke. means controlled by the pilot valve during by the reversing valve for rapid initial operation 25 Number of the reversing valve after complete operation of the pilot valve, and means for regulating the speed of the reversing valve after 'a predetermined range of rapid movement thereof, producing a. gradual changeover of the reversing valve connections.

ALBERT M. LANE. KINGSTON V. TURKPATRICK. ROBERT A. ERSKINE.

REFERENCES CITED I The lfollowing references are oi record in the le of this patent:

. UNITED STATES PATENTS Name Date Stone Apr. 8, 1941 Twyman Dec. 23, 1941 Miller Dec. 1, 1942 

